The present invention relates to mechanical seat suspensions and more particularly, to seat suspensions having a height adjustment capability and those used in vehicles like trucks.
A continuing need exists for seat suspensions which allow for height adjustment to a plurality of positions, which provide a substantially linear suspension curve in each position and which allow for a low suspension profile to be used within a confined space such as a truck cab but which provide maximum and minimum height positioning to accommodate a wide variety of vehicle operators.
Some mechanical seat suspensions utilize cams, cam followers, and lever arms such as U.S. Pat. No. 4,448,386 to Moorhouse et al. and U.S. Pat. No. 4,856,763 to Brodersen et al. Such seat suspensions, however, do not offer the simplistic height adjustment capabilities, smooth suspension characteristics and mechanical advantages of the present invention.
Other current seat suspension systems utilize a bell crank and pivot assembly which includes a lever arm which depends from the bell crank and ends at a roller which rests on a bridge extending upward from a lower suspension housing. Such systems have drawbacks including having limited height adjustment capabilities, requiring substantial space and are unable to provide a low profile or to maximize ride zone, and require a hardened roller which causes a rough ride which is felt by a seat occupant.
The seat suspension of the present invention overcomes the limitations of the prior art. Further, the present invention provides multiple position height adjustment while also providing very low profile mechanics, substantially linear load deflection characteristics of travel versus force, and eliminates the need for cam followers and surfaces which require hardened surfaces, narrow tolerances, and can cause a rougher riding suspension.